Bone stabilization member with bone screw retention mechanism

ABSTRACT

A spinal implant for stabilizing first and second vertebrae. The spinal implant includes an intervertebral spacer and a bone stabilization member configured to be coupled to the intervertebral spacer. The bone stabilization member includes a plurality of bone screw openings and a plurality of bone screws extendable through the bone screw openings to secure the bone stabilization member to the vertebrae. A retention member, which is slidably coupled to the bone stabilization member, is linearly slidable between a first position and a second position while coupled to the bone stabilization member. In the first position, each of the bone screws is permitted to be inserted into the bone screw openings, and in the second position the retention member at least partially covers each of the bone screw openings to prevent a bone screw from backing out of the respective bone screw opening.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 13/560,598, filed Jul. 27, 2012, the completedisclosure of which is herein incorporated by reference.

TECHNICAL FIELD

The disclosure is directed to bone stabilization members configured forsecurement between vertebrae with bone screws and an associated bonescrew retention mechanism configured to prevent the bone screws frombacking out of the vertebrae. More particularly, the disclosure isdirected to a supplemental fixation system for an intervertebral spacerincluding a bone screw retention mechanism configured to prevent bonescrews from backing out of the vertebrae.

BACKGROUND

A variety of devices are known in the art for fixation to the spine insurgical procedures, such as corpectomies and discectomies, for treatingspinal conditions in order to alleviate pain or otherwise stabilize thevertebral segment. During a spinal fixation procedure, after removal ofa spinal disc and/or vertebra an intervertebral implant may be installedbetween a first vertebra and a second vertebra to maintain the properspacing and/or lordosis between the vertebrae and restore stability tothe spine. In some instances, the intervertebral implant may be securedto the vertebrae with bone screws. In some instances, an intervertebralspacer may be positioned between the vertebral bodies of the vertebraeand a bone stabilization member, coupled to the intervertebral spacer,may be provided as a supplemental fixation structure to inhibitmigration of the intervertebral spacer until bone fusion occurs.

Accordingly, it is desirable to provide alternative bone stabilizationconstructs, including supplemental fixation structures forintervertebral spacers and other intervertebral implants, to providestabilization of a spinal segment. Furthermore, it may be desirable toprovide a bone screw retention mechanism with the bone stabilizationconstruct to prevent the associated bone screws from postoperativelybacking out of the vertebrae.

SUMMARY

The disclosure is directed to several alternative designs, materials andmethods of manufacturing medical device structures and assemblies, anduses thereof.

Accordingly, one illustrative embodiment is a bone stabilizationconstruct configured to be secured to a first bony structure and asecond bony structure. The bone stabilization construct includes a bonestabilization member and a retention member coupled to the bonestabilization member. The bone stabilization member includes a pluralityof bone screw openings, such as a first bone screw opening configured toreceive a first bone screw therethrough for securing the bonestabilization member to the first bony structure and a second bone screwopening configured to receive a second bone screw therethrough forsecuring the bone stabilization member to the second bony structure. Insome instances the bone stabilization member may include additional bonescrew openings, such as a third bone screw opening configured to receivea third bone screw therethrough for securing the bone stabilizationmember to the second bony structure. The retention member is configuredto be linearly slidable between a first position and a second positionwhile coupled to the bone stabilization member. In the first position,the retention member does not appreciably block any of the first andsecond bone screw openings thus permitting bone screws to be insertedinto the first and second bone screw openings. For example, in someinstances the retention member may not extend across any portion of anyof the first and second bone screw openings. In the second position theretention member at least partially covers each of the first and secondbone screw openings to prevent a bone screw from backing out of therespective bone screw opening. In embodiments including a third bonescrew opening, in the first position, the retention member mayadditionally not appreciably block any of the third bone screw openingthus permitting a bone screw to be inserted into the third bone screwopening. For example, in some instances the retention member may notextend across any portion of any of the first, second and third bonescrew openings. In the second position the retention member may at leastpartially cover each of the first, second and third bone screw openingsto prevent a bone screw from backing out of the respective bone screwopening.

Another illustrative embodiment is a spinal implant for positioningbetween a first vertebra and a second vertebra of a spinal column. Thespinal implant includes an intervertebral spacer configured forplacement between a vertebral body of the first vertebra and a vertebralbody of the second vertebra and a bone stabilization member configuredto be coupled to the intervertebral spacer. The bone stabilizationmember includes a first bone screw opening and a second bone screwopening. The spinal implant also includes a first bone screw extendablethrough the first bone screw opening to secure the bone stabilizationmember to the first vertebra and a second bone screw extendable throughthe second bone screw opening to secure the bone stabilization member tothe second vertebra. A retention member is slidably coupled to the bonestabilization member. The retention member is linearly slidable betweena first position and a second position while coupled to the bonestabilization member. In the first position the first and second bonescrews are permitted to be inserted into the first and second bone screwopenings, respectively, and in the second position the retention memberprevents the first and second bone screws from being removed from thefirst and second bone screw openings. In some instances the bonestabilization member may include a third bone screw opening and thespinal implant may include a third bone screw extendable through thesecond bone screw opening to secure the bone stabilization member to thesecond vertebra. In the first position the first, second and third bonescrews are permitted to be inserted into the first, second and thirdbone screw openings, respectively, and in the second position theretention member prevents each of the first, second and third bonescrews from being removed from the first, second and third bone screwopenings.

Yet another illustrative embodiment is a method of retaining a pluralityof bone screws to a bone stabilization member. The method includesinserting a first bone screw through a first bone screw opening of abone stabilization member with a retention member coupled to the bonestabilization member in a first position, inserting a second bone screwthrough a second bone screw opening of the bone stabilization memberwith the retention member coupled to the bone stabilization member inthe first position, and inserting a third bone screw through a thirdbone screw opening of the bone stabilization member with the retentionmember coupled to the bone stabilization member in the first position.Thereafter, the retention member is slid linearly from the firstposition to a second position while coupled to the bone stabilizationmember. The retention member is then locked in the second position. Theretention member prevents each of the first, second and third bonescrews from being removed from the first, second and third bone screwopenings, respectively, when locked in the second position.

The above summary of some example embodiments is not intended todescribe each disclosed embodiment or every implementation of theaspects of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The aspects of the disclosure may be more completely understood inconsideration of the following detailed description of variousembodiments in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of an exemplary intervertebral implantincluding an intervertebral spacer and a supplemental fixationstructure;

FIG. 2 is an exploded view of the intervertebral spacer and the bonestabilization construct of the intervertebral implant of FIG. 1;

FIG. 3 is a top view of the intervertebral spacer and the bonestabilization construct of the intervertebral implant of FIG. 1;

FIG. 4 is a perspective view of the bone stabilization construct of FIG.1 with the retention member in a first, unlocked position;

FIG. 5 is a view generally along the central longitudinal axis of afirst bone screw opening of the bone stabilization construct, with theretention member in a first, unlocked position;

FIG. 6 is a view generally along the central longitudinal axis of secondand third bone screw openings of the bone stabilization construct, withthe retention member in a first, unlocked position;

FIG. 7 is a perspective view of the bone stabilization construct of FIG.1 with the retention member in a second, locked position;

FIG. 8 is a view generally along the central longitudinal axis of afirst bone screw opening of the bone stabilization construct, with theretention member in a second, locked position;

FIG. 9 is a view generally along the central longitudinal axis of secondand third bone screw openings of the bone stabilization construct, withthe retention member in a second, locked position;

FIG. 10 is a top view of the bone stabilization construct with bonescrews extending through the bone screw openings;

FIG. 11 is a perspective view of another exemplary intervertebralimplant including an intervertebral spacer and a supplemental fixationstructure; and

FIGS. 12-14 illustrate an illustrative method of installing theintervertebral implant to first and second vertebrae of a spinal column.

While the aspects of the disclosure are amenable to variousmodifications and alternative forms, specifics thereof have been shownby way of example in the drawings and will be described in detail. Itshould be understood, however, that the intention is not to limitaspects of the disclosure to the particular embodiments described. Onthe contrary, the intention is to cover all modifications, equivalents,and alternatives falling within the spirit and scope of the disclosure.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the term “about” may be indicative asincluding numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

Although some suitable dimensions, ranges and/or values pertaining tovarious components, features and/or specifications are disclosed, one ofskill in the art, incited by the present disclosure, would understanddesired dimensions, ranges and/or values may deviate from thoseexpressly disclosed.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The detailed description and the drawings, which are notnecessarily to scale, depict illustrative embodiments and are notintended to limit the scope of the disclosure. The illustrativeembodiments depicted are intended only as exemplary. Selected featuresof any illustrative embodiment may be incorporated into an additionalembodiment unless clearly stated to the contrary.

An exemplary embodiment of an intervertebral implant 10 including anintervertebral spacer 20 and a supplemental fixation structure 35 isshown in FIG. 1. The intervertebral implant 10 may be configured to besecured between a first vertebra and a second vertebra of a spinalcolumn, such as during a discectomy or corpectomy procedure. Forexample, one or more, or a plurality of bone screws 32 may be utilizedto attach the intervertebral implant 10 to a vertebral body of asuperior vertebra and one or more, or a plurality of bone screws 32 maybe utilized to attach the intervertebral implant 10 to a vertebral bodyof an inferior vertebra. It is noted that in the illustrative embodimentthe intervertebral implant 10 includes a bone stabilization construct 30coupled to an intervertebral spacer 20, however, in other embodimentsthe intervertebral implant 10 may include a bone stabilization construct30 configured for securing to vertebrae of a spinal column without anintervertebral spacer 20.

Turning to FIGS. 2 and 3, the intervertebral spacer 20 may be sized andconfigured to be positioned between a vertebral body of a superiorvertebra and a vertebral body of an inferior vertebra during adiscectomy or corpectomy procedure, for example, to maintain properspacing between the vertebrae. The intervertebral spacer 20 may includea posterior side 21, an anterior side 24 opposite the posterior side 21,lateral sides 22, 23 extending between the posterior side 21 and theanterior side 24, a superior side 25 configured to face or contact aninferior surface of a vertebral body of a superior vertebra, and aopposing inferior side 26 configured to face or contact a superiorsurface of a vertebral body of an inferior vertebra. The superior and/orinferior sides 25, 26 may include teeth, grooves or other anti-migrationstructures to engage the vertebral bodies to assist stabilizing theintervertebral spacer 20 between the vertebrae. Additionally, in someinstances the intervertebral spacer 20 may include a cavity 28, or aplurality of cavities, which may be filled with bone growth material tofacilitate postoperative fusion between the superior and inferiorvertebrae.

The intervertebral spacer 20 may be constructed of a polymer material,such as polyetheretherketone (PEEK), a metallic material, such asstainless steel or titanium, or any other suitable biocompatiblematerial, as desired.

The supplemental fixation structure 35, shown as a bone stabilizationconstruct 30 may be coupled or couplable to the intervertebral spacer20. I some instances, the bone stabilization construct 30 may be a boneplate, or other structure configured to be secured to vertebrae or otherbony structures. The bone stabilization construct 30 may include a bonestabilization member 40 and a retention member 50 movably coupled to thebone stabilization member 40. For example, the retention member 50 maybe slidably coupled to the bone stabilization member 40 such that theretention member 50 is only permitted to slide in first and secondopposite directions within a single plane.

The bone stabilization member 40 and/or the retention member may beconstructed of a polymer material, such as polyetheretherketone (PEEK),a metallic material, such as stainless steel or titanium, or any othersuitable biocompatible material, as desired.

The bone stabilization construct 30 may be configured to be coupled tothe intervertebral spacer 20 by any desired means. For example, the bonestabilization member 40 may include an engagement structure configuredto engage or mate with an engagement structure of the intervertebralspacer 20, or a fastener, such as a threaded fastener, may be used tocouple the bone stabilization member 40 to the intervertebral spacer 20.In other instances, the bone stabilization member 40 may be integrallycoupled to the intervertebral spacer 20 by forming the bonestabilization member 40 and the intervertebral spacer 20 as a unitarystructure, and movably coupling the retention member 50 to the bonestabilization member 40 of the unitary structure.

In the illustrative embodiment, the bone stabilization member 40 may beconfigured to be snap fit to or otherwise interlock with an anteriorportion of the intervertebral spacer 20. For example the bonestabilization member 40 may include first and second arms 42 configuredto interlock in channels 29 of the intervertebral spacer 20.Furthermore, a tang 41 on each arm 42, which may be flexibly deflectedrelative to the arm 42, may be configured to engage in opposing openingsor notches 31 formed in the intervertebral spacer 20 to furtherinterlock or engage the bone stabilization member 40 with theintervertebral spacer 20. For instance, the tangs 41 may be deflectedoutward as an anterior portion of the intervertebral spacer 20 ispositioned between the arms 42 and then return to or toward anequilibrium position as the tangs 41 engage in the openings or notches31 of the intervertebral spacer 20.

As shown in FIG. 4, the bone stabilization member 40 may include aplurality of openings to receive bone screws therethrough to secure thebone stabilization member 40 to vertebrae. For example, the bonestabilization member 40 may include a first bone screw opening 41configured to receive a first bone screw 32 therethrough to anchor thebone stabilization member 40 to a first bony structure (e.g., a first,inferior vertebra), a second bone screw opening 42 configured to receivea second bone screw 32 therethrough to anchor the bone stabilizationmember 40 to a second bony structure (e.g., a second, superiorvertebra), and a third bone screw opening 43 configured to receive athird bone screw 32 therethrough to anchor the bone stabilization member40 to the second bony structure (e.g., the second, superior vertebra).The second bone screw opening 42 may be positioned proximate a firstlateral edge of the bone stabilization member 40, the third bone screwopening 43 may be positioned proximate an opposite second lateral edgeof the bone stabilization member 40, and the first bone screw opening 41may be positioned at a location intermediate the second bone screwopening 42 and the third bone screw opening 43. The first, second andthird bone screw openings 41, 42, 43 may be arranged such that the firstbone screw opening 41 is offset from, and not aligned between the secondand third bone screw openings 42, 43. In other words, the first bonescrew opening 41 may be arranged so that a line extending between thecentral axes of the second and third bone screw openings 42, 43 does notpass through the central axis of the first bone screw opening 41.

Referring to FIGS. 5 and 6, the central axis X₁ of the first bone screwopening 41 may be offset from the midplane M of the intervertebralimplant 10, and thus the first bone screw opening 41 may be positionedcloser to the central axis X₃ of the third bone screw opening 43 than tothe central axis X₂ of the second bone screw opening 42, while thecentral axes X₂, X₃ of the second and third bone screw openings 42, 43may be spaced equidistant from the midplane M on either side of themidplane M. The midplane M is an imaginary plane extending in asuperior/inferior direction extending through the middle of theintervertebral implant 10 equidistant between lateral sides of theintervertebral spacer 20. By offsetting the first bone screw opening 41away from the midplane M, the spacing of the locking screw 52 and thefirst bone screw opening 41 may be arranged to accommodate a wider rangeof heights of the bone stabilization member 40, and thus theintervertebral spacer 20, therefore permitting bone stabilizationmembers 40 and intervertebral spacers 20 having a shorter height to beconstructed.

The retention member 50 may be configured to be selectively actuatablebetween a first position (shown in FIGS. 4-6) permitting bone screws 32to be inserted through the bone screw openings 41, 42, 43 and a secondposition (shown in FIGS. 7-9) preventing the bone screws 32 from backingout or being removed from the bone screw openings 41, 42, 43 once thebone stabilization member 40 is secured to the bony structures with thebone screws 32. The retention member 50 may be configured tosimultaneously cover or be positioned over at least a portion of each ofthe bone screw openings 41, 42, 43 in the second, locked position, thuspreventing each of the bone screws 32 from backing out.

In the illustrative embodiment, the retention member 50 may be slidablycoupled to the bone stabilization member 40, permitting linear actuationof the retention member 50 relative to the bone stabilization member 40along a longitudinal axis to slide the retention member 50 between thefirst, unlocked position and the second, locked position. Thus, in someembodiments, the retention member 50 may be linearly slidable betweenthe first and second positions without rotational movement of theretention member 50.

A locking screw 52 may be provided to couple the retention member 50 tothe bone stabilization member 40. For example, the locking screw 52 mayextend through an elongated opening 56 of the retention member 50 andthreadably engage a threaded bore 48 of the bone stabilization member40. In some instances, the locking screw 52 may be prevented from beingfully unthreaded from the threaded bore 48 during use, thus insuringthat the locking screw 52 will remain with the bone stabilization member40 while the surgeon is installing the bone stabilization construct 30to the bony structures. The elongated opening 56 may have a length and awidth, with the length being greater than the width. The locking screw52 may be permitted to travel along the length of the elongated opening56 as the retention member 50 is moved between the first position andthe second position.

The retention member 50 may also include an engagement structureconfigured to mate with a complementary engagement structure of the bonestabilization member 40. For example, the retention member 50 mayinclude a protrusion 54, such as a dovetail shaped protrusion, sized andconfigured to mate in a slot or channel 44, such as a dovetail shapedslot or channel, in the bone stabilization member 40. The protrusion 54may be configured to slide along the longitudinal axis of the channel 44as the retention member 50 is linearly actuated between the first andsecond positions, without permitting the protrusion 54 from beinguncoupled from the channel 44. In other embodiments, the protrusion 54may be T-shaped to mate with a T-shaped channel, or otherwise shaped toprohibit the protrusion 54 from being removed from the channel 54 in adirection perpendicular to the longitudinal axis of the channel 44 asthe retention member 50 is linearly moved between the first and secondpositions. Engagement of the protrusion 54 within the channel 44 maypermit the retention member 50 to move in first and second oppositedirections relative to the bone stabilization member 40 along thelongitudinal axis of the channel 44, while prohibiting movement of theretention member 50 relative to the bone stabilization member 40 in allother directions. The protrusion 54 and the channel 44 may beconstructed such that the protrusion 54 is at least partially positionedin the channel 44 along the full length of travel of the locking screw52 in the elongated opening 56 of the retention member 50. Additionally,engagement of the protrusion 54 within the channel 44 may retain theretention member 50 in a desired orientation relative to the bonestabilization member 40, as well as provide strength and/or stability tothe portion of the retention member 50 located above the first bonescrew opening 41 and extending toward the third bone screw opening 43.

The elongated opening 56 may be configured such that as the lockingscrew 52 is tightened (e.g., rotation of the locking screw 52 causingthe head of the locking screw 52 to bear against the retention member50), the head of the locking screw 52 engages the rim of the elongatedopening 56. For example, the locking screw 52 may include a driverinterface, such as a hex opening or other standard driver interface (ora specialized driver interface, if desired) to engage with a driver,such as a hex wrench or other standard driver (or a specialized driver)to tighten the locking screw 52. In some instances, it may be desirableto provide a locking screw 52 having a standard driver interface, suchas a hex opening, to facilitate subsequent loosening of the lockingscrew 52 during a revision surgery at a later date, where the medicalpersonnel performing the revision surgery may not have a specializeddriver, but would have access to standardized drivers fitting the driverinterface of the locking screw 52.

As the locking screw 52 is tightened, the head of the locking screw 52may interact with the rim of the elongate opening 56 such that when thehead of the locking screw 52 is pressed against the rim, forcesgenerated between the head of the locking screw 52 and the retentionmember 50 cause the retention member 50 to move toward the secondposition. The rim of the elongate opening 56 may include a seatingportion (visible in FIG. 4) in which the head of the locking screw 52 isseated when the retention member 50 is in the second position. Thus, asthe locking screw 52 is tightened, the head of the locking screw 52moves toward and into the seating portion of the elongated opening 56.Upon sufficient tightening of the locking screw 52, the retention member50 may be firmly secured to the bone stabilization member 40 such thatno further movement of the retention member 50 is permitted.

FIG. 5 illustrates a view of the bone stabilization construct 30generally along the central longitudinal axis X₁ of the first bone screwopening 41 of the bone stabilization construct 30, with the retentionmember 50 in the first, unlocked position. FIG. 6 illustrates a view ofthe bone stabilization construct 30 generally along the centrallongitudinal axes X₂, X₃ of the second and third bone screw openings 42,43 of the bone stabilization construct 30, with the retention member 50in the first, unlocked position. In the first position, the retentionmember 50 may be loosely coupled to the bone stabilization member 40with the locking screw 52 and the protrusion 54 in the channel 44. Forexample, the retention member 50 may be moved into the first position byraising the retention member 50 toward the upper side of the bonestabilization member 40, and thus toward the superior side 25 of theintervertebral spacer 20, such that the loosened locking screw 52 ismoved into a lower portion of the elongated opening 56. In the firstposition the first, second and third bone screws 32 may be permitted tobe inserted into the first, second and third bone screw openings 41, 42,43, respectively, without being inhibited by the retention member 50.For example, in the first position, the retention member 50 may be clearof and not cover or extend across any portion of any of the first,second and third bone screw openings 41, 42, 43 or otherwise may notsubstantially block any of the first, second and third bone screwopenings 41, 42, 43, and thus permit the first, second and third bonescrews 32 to be inserted into the first, second and third bone screwopenings 41, 42, 43, respectively. In other words, in some instances, inthe first position all portions of the retention member 50 may belocated radially outward of and not impede into the diameter of any ofthe first, second and third bone screw openings 41, 42, 43, for example.

FIG. 7 illustrates the bone stabilization construct 30 with theretention member 50 moved downward to the second position upontightening the locking screw 52. As the retention member 50 is movedtoward the second position, the locking screw 52 may travel in theelongated opening 56 toward the seating portion of the elongated opening56 at the upper extent of the elongated opening 56. In the secondposition, portions of the retention member 50 may cover or extend acrossportions of each of the first, second and third bone screw openings 41,42, 43 and thus the heads of respective bone screws 32 extendingtherethrough to prevent the bone screws 32 from backing out of the bonescrew openings 41, 42, 43. For example, in the second position theretention member 50 may include a first portion, such as an arcuate edge57 defining an arcuate cutout portion of the retention member 50 atleast partially covering the first bone screw opening 41 (and associatedbone screw 32), a second portion, such as a first tab 58, at leastpartially covering the second bone screw opening 42 (and associated bonescrew 32), and a third portion, such as a second tab 59, at leastpartially covering the third bone screw opening 43 (and associated bonescrew 32).

FIG. 8 illustrates a view of the bone stabilization construct 30generally along the central longitudinal axis X₁ of the first bone screwopening 41 of the bone stabilization construct 30, with the retentionmember 50 in the second, locked position. FIG. 9 illustrates a view ofthe bone stabilization construct 30 generally along the centrallongitudinal axes X₂, X₃ of the second and third bone screw openings 42,43 of the bone stabilization construct 30, with the retention member 50in the second, locked position. In the second position, the retentionmember 50, fixedly secured to the bone stabilization member 40 viatightening the locking screw 52, may at least partially cover each ofthe first, second and third bone screw openings 41, 42, 43 to prevent abone screw 32 from backing out of the respective bone screw opening. Inother words, in the second position a portion of the retention member 50may be located radially inward of and impede into the diameter of eachof the first, second and third bone screw openings 41, 42, 43.

As shown in FIG. 10, the second and third bone screw openings 42, 43 maybe configured such that the central axis of the associated bone screws32 extend along the central axis of the second and third bone screwopenings 42, 43 generally parallel to the midplane M of theintervertebral implant 10. Since the first bone screw opening 41 isoffset from the midplane M, the first bone screw opening 41 may beconfigured to angle the distal tip of the bone screw 32 extendingtherethrough toward the midplane M from the first bone screw opening 41.For example, the first bone screw opening 41 may be configured such thatthe central axis of the first bone screw 32, which may be coaxial withthe central axis X₁ of the first bone screw opening 41, may be at anangle θ to the midplane M. For example, the central axis of the firstbone screw 32 may extend at an angle θ in the range of about 1 to 10degrees, for example, about 1, about 2, about 3, about 4, about 5, about6, about 7, about 8, about 9 or about 10 degrees from the midplane M, ifdesired, in order to angle the distal tip of the bone screw 32 towardthe midplane M.

Another illustrative embodiment of an intervertebral implant 110 isshown in FIG. 11. The intervertebral implant 110 may share manysimilarities to the intervertebral implant 10. For example, theintervertebral implant 110 may include an intervertebral spacer 120 anda supplemental fixation structure 135 to facilitate securement of theintervertebral implant 110 between a first vertebra and a secondvertebra of a spinal column. For example, one or more, or a plurality ofbone screws 132 may be utilized to attach the intervertebral implant 110to a vertebral body of a superior vertebra and one or more, or aplurality of bone screws 132 may be utilized to attach theintervertebral implant 110 to a vertebral body of an inferior vertebra.

The supplemental fixation structure 135, shown as a bone stabilizationconstruct 130 may be coupled or couplable to the intervertebral spacer120. The bone stabilization construct 130 may include a bonestabilization member 140 and a retention member 150 movably coupled tothe bone stabilization member 140. For example, the retention member 150may be slidably coupled to the bone stabilization member 140 such thatthe retention member 150 is only permitted to slide linearly in firstand second opposite directions within a single plane.

A locking screw 152 may be provided to couple the retention member 150to the bone stabilization member 140. For example, the locking screw 152may extend through an elongated opening 156 of the retention member 150and threadably engage a threaded bore of the bone stabilization member140. As the locking screw 152 is tightened, the head of the lockingscrew 152 may interact with the rim of the elongate opening 156 suchthat when the head of the locking screw 152 is pressed against the rim,forces generated between the head of the locking screw 152 and theretention member 150 cause the retention member 150 to move from thefirst, unlocked position toward the second, locked position to preventthe bone screws 132 from backing out.

FIG. 11 illustrates a configuration of an intervertebral implant 110having a height less than the height of the intervertebral implant 10shown in FIG. 1. As shown in FIG. 11, offsetting the first bone screwopening 141 from the midplane M of the intervertebral implant 110 to afirst side of the midplane M, while offsetting the locking screw 152 andassociated elongated opening 156 to a second side of the midplane Mopposite the first bone screw opening 141, may permit the constructionof intervertebral implants having a smaller height dimension than thecombined heights of the elongated opening 156 and the first bone screwopening 141. Accordingly, a set of intervertebral implants having arange of heights may be provided during a surgical procedure, includingheights less than the combined heights of the elongated opening 156 andthe first bone screw opening 141 without reducing the size of thelocking screw 152 and/or the bone screws 132.

FIGS. 12-14 illustrate one exemplary method of installing theintervertebral implant 10 to first and second vertebrae V₁, V₂ of aspinal column. The intervertebral implant 10 may maintain the properspacing and/or lordosis between the vertebrae V₁, V₂ and restorestability to the spine.

n some instances, the intervertebral implant 10 may be provided with thebone stabilization construct 30 coupled to the intervertebral spacer 20.If not already coupled to the intervertebral spacer 20, the bonestabilization construct 30 may be intraoperatively coupled to theintervertebral spacer 20 prior to installing the intervertebral implant10. It is noted that in some instances, the bone stabilization construct30 may be coupled to or otherwise interlocked with the intervertebralspacer 20 subsequent to installing the intervertebral spacer 20 betweenthe vertebrae V₁, V₂, if desired. The bone stabilization construct 30may be coupled to the anterior portion of the intervertebral spacer 20.For example, the bone stabilization member 40 may be snap coupled to theintervertebral spacer 20 such that the first and second arms 42 of thebone stabilization member 40 are positioned on either side of theanterior portion and the tangs 41 are engaged in the openings or notches31 of the intervertebral spacer 20.

As shown in FIG. 12, after preparing a space between the vertebralbodies of the vertebrae V₁, V₂, such as during a discectomy orcorpectomy procedure, the intervertebral spacer 20 and the bonestabilization construct 30 of the intervertebral implant 10 may beinserted between the vertebral body of the first vertebra V₁ and thevertebral body of the second vertebra V₂ using an insertion instrument(not shown). For instance, the intervertebral implant 10, including theintervertebral spacer 20 and/or the bone stabilization construct 30, maybe inserted using an anterior approach, in which the posterior side ofthe intervertebral spacer 20, which may be considered the leading side,is inserted first and directed posteriorly into the space between thevertebrae V₁, V₂, from the anterior side of the spinal column.

The inferior surface of the intervertebral spacer 20 may be configuredto engage a superior surface of the vertebral body of the first vertebraV₁ and the superior surface of the intervertebral spacer 20 may beconfigured to engage an inferior surface of the vertebral body of thesecond vertebra V₂. In some instances, the superior and inferiorsurfaces may be generally parallel, disposed at an angle, or have acurvature to accommodate the proper spacing and/or lordosis between thevertebrae V₁, V₂. If desired, the cavity 28 may be filled with bonegrowth material prior to inserting the intervertebral spacer 20 topromote subsequent fusion between the vertebrae V₁, V₂.

Thereafter, as shown in FIG. 13, bone screws 32 may be inserted throughthe bone screw openings 41, 42, 43 of the bone stabilization member 40and screwed into the vertebrae V₁, V₂ while the retention member 50 isin the first, unlocked position. For instance, a first bone screw 32 maybe inserted through the first bone screw opening 41 of the bonestabilization member 40 with the retention member 50 coupled to the bonestabilization member 40 in the first position. The first bone screw 32may be screwed into the vertebral body of the first vertebra V₁ toanchor the bone stabilization member 40 to the first vertebra V₁. Asecond bone screw 32 may be inserted through the second bone screwopening 42 of the bone stabilization member 40 and a third bone screw 32may be inserted through the third bone screw opening 43 with theretention member 50 coupled to the bone stabilization member 40 in thefirst position. The second and third bone screws 32 may be screwed intothe vertebral body of the second vertebra V₂ to anchor the bonestabilization member 40 to the second vertebra V₂.

Thereafter, the retention member 50 may be moved to the second positionto extend across at least a portion of each of the first, second andthird bone screw openings 41, 42, 43 to prevent the bone screws 32 frombacking out of the bones. For example, as shown in FIG. 14, theretention member 50 may be slid linearly relative to the bonestabilization member 40 from the first position to the second positionwhile coupled to the bone stabilization member 40, and thereafter lockedin the second position. For example, the locking screw 52 may betightened (e.g. rotated with a driver). By rotating the locking screw 52threadably coupled to the bone stabilization member 40, the lockingscrew 52 may exert a force on the rim of the elongated opening 56 of theretention member 50 to slide the retention member 50 linearly from thefirst position to the second position. The protrusion 54 may followalong the channel 44 of the bone stabilization member 40 as theretention member 50 moves toward the second position. The locking screw52 may be rotated until the locking screw 52 has traveled along thelength of the elongated opening 56 a sufficient distance such that thehead of the locking screw 52 is seated in the seating portion of theelongate opening 56. Sufficient torque may be applied to the lockingscrew 52 to securely seat the head of the locking screw 52 in theseating portion and secure the retention member 50 from further movementrelative to the bone stabilization member 40. When locked in the secondposition, the retention member 50 may prevent each of the first, secondand third bone screws 32 from being removed from the first, second andthird bone screw openings 41, 42, 43, respectively.

It is noted that in other embodiments, the bone stabilization construct30, 130 may be used in other applications, such as trauma to secure twobony structures (e.g. two bony portions of a single bone, or a firstbone and a second bone) with a plurality of bone screws 32, 132. In somesuch applications, it is noted that the bone stabilization construct 30,130 may be used without the intervertebral spacer 20, 120. In someinstances, the bone stabilization member 30, 130 may be secured to twobony structures with a first bone screw 32, 132 screwed into a firstbony structure and second and third bone screws 32, 132 screwed into asecond bony structure.

Those skilled in the art will recognize that aspects of the presentdisclosure may be manifested in a variety of forms other than thespecific embodiments described and contemplated herein. Accordingly,departure in form and detail may be made without departing from thescope and spirit of the present disclosure as described in the appendedclaims.

What is claimed is:
 1. A spinal implant for positioning between a firstvertebra and a second vertebra, the spinal implant comprising: anintervertebral spacer configured for placement between a vertebral bodyof the first vertebra and a vertebral body of the second vertebra; abone stabilization member configured to be coupled to the intervertebralspacer; the bone stabilization member including a first bone screwopening, a second bone screw opening, and a third bone screw opening; afirst bone screw extendable through the first bone screw opening tosecure the bone stabilization member to the first vertebra; a secondbone screw extendable through the second bone screw opening to securethe bone stabilization member to the second vertebra; a third bone screwextendable through the third bone screw opening to secure the bonestabilization member to the second vertebra; a retention member coupledto the bone stabilization member, the retention member linearly slidablebetween a first position and a second position while coupled to the bonestabilization member; and a locking screw coupling the retention memberto the bone stabilization member; wherein in the first position thefirst, second and third bone screws are permitted to be inserted intothe first, second and third bone screw openings, respectively, and inthe second position the retention member prevents the first, second andthird bone screws from being removed from the first, second and thirdbone screw openings.
 2. The spinal implant of claim 1, wherein theretention member includes a protrusion slidably engaged in a slot of thebone stabilization member.
 3. The spinal implant of claim 1, wherein thelocking screw extends through an elongate opening of the retentionmember into a threaded bore of the bone stabilization member, theelongate opening having a length greater than a width of the elongateopening; wherein the locking screw travels along the length of theelongate opening as the locking screw is rotated into the threaded boreto move the retention member from the first position to the secondposition.
 4. The spinal implant of claim 1, wherein the intervertebralspacer has a midplane extending in a superior/inferior direction betweenlateral sides of the intervertebral spacer; wherein the first bone screwopening is located between the second bone screw opening and the thirdbone screw opening; wherein the first bone screw opening is offset to afirst side of the midplane; and wherein the locking screw is offset to asecond side of the midplane opposite the first side.
 5. The spinalimplant of claim 1, wherein the first bone screw opening is locatedbetween the second bone screw opening and the third bone screw opening;wherein the intervertebral spacer has a midplane extending in asuperior/inferior direction between lateral sides of the intervertebralspacer; wherein the first bone screw opening is offset to one side ofthe midplane; and wherein the first bone screw angles toward themidplane when extended through the first bone screw opening.
 6. Thespinal implant of claim 1, wherein the retention member includes a firsttab configured to at least partially cover the second bone screw openingin the second position and a second tab configured to at least partiallycover the third bone screw opening in the second position.
 7. The spinalimplant of claim 6, wherein the retention member includes an arcuateedge defining an arcuate cutout portion of the retention memberconfigured to at least partially cover the first bone screw opening inthe second position.
 8. A spinal implant for positioning between a firstvertebra and a second vertebra, the spinal implant comprising: anintervertebral spacer configured for placement between a vertebral bodyof the first vertebra and a vertebral body of the second vertebra; abone stabilization member configured to be coupled to the intervertebralspacer; the bone stabilization member including a first bone screwopening, a second bone screw opening, and a third bone screw opening; afirst bone screw extendable through the first bone screw opening tosecure the bone stabilization member to the first vertebra; a secondbone screw extendable through the second bone screw opening to securethe bone stabilization member to the second vertebra; a third bone screwextendable through the third bone screw opening to secure the bonestabilization member to the second vertebra; a retention member coupledto the bone stabilization member, the retention member movable between afirst position and a second position while coupled to the bonestabilization member; and a locking screw coupling the retention memberto the bone stabilization member, wherein rotation of the locking screwabout a rotational axis causes the retention member to move in adirection generally perpendicular to the rotational axis; wherein thefirst bone screw opening is located between the second bone screwopening and the third bone screw opening; wherein the intervertebralspacer has a midplane extending in a superior/inferior direction betweenlateral sides of the intervertebral spacer; wherein the first bone screwopening is offset to one side of the midplane; and wherein the firstbone screw angles toward the midplane when extended through the firstbone screw opening.
 9. The spinal implant of claim 8, wherein in thesecond position the retention member prevents at least one of the first,second and third bone screws from being removed from bone stabilizationmember.
 10. The spinal implant of claim 8, wherein rotation of thelocking screw causes the locking screw to travel along an elongateopening of the retention member.
 11. The spinal implant of claim 10,wherein the locking screw interacts with a rim of the elongate openingsuch that when a head of the locking screw is pressed against the rimthe retention member moves toward the second position.
 12. The spinalimplant of claim 8, wherein the retention member includes a protrusionslidably disposed in a slot of the bone stabilization member.
 13. Thespinal implant of claim 12, wherein the protrusion is dovetail shapedand the slot is dovetail shaped to mate with the dovetail shape of theprotrusion.
 14. The spinal implant of claim 8, wherein the retentionmember is configured to simultaneously cover at least a portion of eachof the first, second and third bone screw openings.